Chapter 69 Seizure Disorders
PATHOPHYSIOLOGY
A seizure is a sudden, transient alteration in brain function as a result of abnormal neuronal activity and excessive cerebral electrical discharge. This activity can be partial or focal, originating in a specific area of the cerebral cortex—or generalized, involving both hemispheres of the brain. It is indicative of underlying brain pathology. Clinical manifestations vary, depending on the area(s) of brain involvement. The types of seizure affecting children and adolescents are listed in Box 69-1, which is the international classification of epileptic seizures created in 1981 by the International League Against Epilepsy. This classification is currently being revised.
Box 69-1 The International Classification of Epileptic Seizures
I. Partial (focal, local) seizures
II. Generalized seizures (convulsive or nonconvulsive, all associated with loss of consciousness)
III. Unclassified epileptic seizures—cannot be classified because of inadequate or incomplete data; includes some neonatal seizures (e.g., rhythmic eye movements, chewing, and swimming movements)
Adapted from Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for revised clinical and electroencephalographic classification of epileptic seizures. Epilepsia 22:489–501, 1981 currently under revision (p. 20, Dreifuss, 1996).
If an area of the brain is affected, a focal seizure occurs, and if the whole brain is affected, a generalized seizure occurs. Any type of seizure can secondarily generalize. Before a focal seizure, a person may have a preictal (preseizure) phase consisting of varied symptoms, which may include a feeling, a subjective sensation, or a physical symptom signifying that a seizure will occur. In younger children the preictal phase may consist of a mood change or clingy type behavior that the parent will say occurs before the seizure.
A seizure is referred to as the ictal phase. Most seizures last less than 5 minutes, the majority less than 2 minutes. Seizure symptoms can include vocal, motor, cognitive, respiratory, and autonomic components, change in consciousness, and/or loss of consciousness. The postictal phase may occur after the seizure, and symptoms may include headache, fatigue, confusion, transient focal weakness (Todd’s paresis or paralysis), speech difficulty, amnesia, muscle aches, sleepiness, and so forth. Seizures can be further classified as idopathic if there is not identifiable cause, symptomatic if a cause is identified, or cryptogenic if an unidentified brain disorder is suspected.
The causes of seizure include perinatal factors, anoxia, congenital malformations of the brain, genetic factors, infectious disease (encephalitis, meningitis), febrile illness, metabolic disorders, trauma, neoplasms, toxins, circulatory disturbances, and degenerative diseases of the nervous system. Seizure triggers can include sleep deprivation, poor nutrition and hydration, photic stimulation, nonadherence to aspects of the treatment plan, stress, illness, certain medications, hormonal issues, and alcohol or drug use or withdrawal.
Epilepsy is a disorder characterized by recurrent, spontaneous, unprovoked seizures that are primarily of cerebral origin; it indicates the presence of underlying brain dysfunction. Epilepsy is not a disease in itself but a disorder, which can include possible effects on functional status, social status, emotional status, cognition, perception of health status, and quality of life. When a person is diagnosed with epilepsy, the seizure is classified according to type. Once the seizure type is known, the age of onset and the medical history, including development, physical examination, and electroencephalogram (EEG) pattern, are used to determine if the epilepsy fits into an epilepsy syndrome. Epilepsy syndromes common in children include juvenile absence epilepsy, benign centrotemporal epilepsy, and juvenile myoclonic epilepsy. Other disorders have clinical symptoms that can look like seizures. It is important to distinguish seizures from breath-holding spells, behavior disorders, cardiac arrrhythmias, anxiety attacks, migraine disorder, movement disorders, nonepileptic seizures, sleep disorders, and syncope.
INCIDENCE
1. Epilepsy and seizures affect 2.5 million Americans of all ages.
2. Of the general population, 10% will experience a seizure at some time in their life.
3. Of the American population, 3% will develop epilepsy by 75 years of age.
4. Epilepsy incidence is highest in those under 2 years and over 65 years of age.
5. Each year 45,000 children under age 15 years develop epilepsy.
6. Infections and metabolic disorders are the most common causes of seizure in children.
7. Etiology of epilepsy is unknown in two thirds of affected individuals.
8. Of all children between 6 months and 5 years of age, 2% to 5% will experience a febrile seizure.
9. Of children with febrile seizures, 2% to 5% will develop epilepsy.
CLINICAL MANIFESTATIONS
See Box 69-1 for clinical manifestations of seizure activity. Seizure disorders may also affect cognitive and functional abilities and emotional status during nonseizure periods.
COMPLICATIONS
Of Epilepsy
1. Cognition: learning disabilities
2. Neurodevelopmental: attention deficit or attention deficit/hyperactivity disorders (ADD/ADHD); speech, gross motor, and fine motor disorders
3. Neurologic: headache, migraines, sudden unexplained death in epilepsy [SUDEP]
4. Psychiatric: behavioral, anxiety-depressive disorders
5. Social challenges: stigma, school or job performance, driving restrictions (different in each state)
LABORATORY AND DIAGNOSTIC TESTS
Tests are ordered based upon the child’s history, examination findings, and seizure description. Refer to Appendix D for normal values and/or ranges of laboratory and diagnostic tests.
1. Complete blood cell count (CBC)—to rule out infection or possible side effects to medication or ketogenic diet–like anemias or bleeding issues
2. Electrolyte panel—to look for possible metabolic or electrolyte causes
3. Urine and serum toxicology screens—to rule out ingestion as possible cause
4. Lumbar puncture—to rule out infection if febrile or concerned about possible meningitis or encephalitis
5. Antiepileptic drug levels—trough level is done to evaluate adherence to plan of care, to determine whether level medication is effective, or to ascertain peak level to determine reasons for side effects or toxicity
6. Urine organic acids and/or serum quantitative amino acids—to detect inborn errors of metabolism as possible cause
7. Routine electroencephalogram (EEG)—standard test for nonfebrile seizure to determine seizure type, epilepsy syndrome, and risk for recurrence; it assists in treatment management decisions. A normal EEG does not rule out epilepsy, and an abnormal EEG does not confirm it. An EEG is a guide for diagnosis and treatment decisions. The EEG is usually done at least 48 hours after the seizure so as not to confuse the findings with postictal slowing. An EEG is usually performed in partially sleep-deprived children to assist in detecting any abnormalities. If possible, the EEG should be done without sedation.
8. Video-EEG: provides video recording of the patient simultaneous with an EEG—to assist in comparing the clinical symptoms with electrographic changes on EEG during the clinical event. It further aids in determining the seizure type and possible epilepsy syndrome. This test is typically used when evaluating treatment failure and/or evaluating a possible candidate for epilepsy surgery.
9. Computed tomography (CT) of the brain—may be done as an emergent scan for quick determination of signs like bleeding, trauma, or tumor when the patient has postictal focal deficits or has not returned to baseline after the seizure.
10. Magnetic resonance imaging (MRI) of the brain—preferred neuroimaging study conducted as more sensitive study of brain at the cellular level. An MRI is done to discover abnormalities that may affect treatment and management planning and as a component of the evaluation for possible epilepsy surgery.
11. Positron emission tomography (PET) or single photon emission computed tomography (SPECT) scans of the brain: nuclear imaging studies that use intravenously administered radioisotopes to evaluate any possible abnormalities of brain metabolic functioning—can help locate the onset of a focal epilepsy; also used as part of the evaluation for possible epilepsy surgery.
12. Speech evaluation—to ascertain the effect of epilepsy on speech reception, expression, and comprehension; also used as part of the evaluation for epilepsy surgery.
13. Neuropsychologic or psychologic evaluation—to ascertain the effect of epilepsy on cognitive skills, gross and fine motor skills, and emotional issues. These evaluations are used as part of the epilepsy surgery evaluation.
14. Physical therapy evaluation—as needed to ascertain gross motor functioning secondary to epilepsy.
15. Occupational therapy evaluation—as needed to determine fine motor problems secondary to epilepsy.
MEDICAL MANAGEMENT
Antiepileptic Drug Therapy
Antiepileptic drug (AED) therapy is the mainstay of medical management. Monotherapy is preferred to polytherapy to decrease potential side effects. The goal is no seizures and no side effects, although this is not always possible. The drug of choice is based on seizure type, epilepsy syndrome, and client variables. Polytherapy may be tried to achieve seizure control in intractable cases. Complete control is achieved in about two thirds of persons with epilepsy who remain on antiepileptic medication for an extended period. Febrile seizure disorder is not treated with antiepileptic drug therapy, since febrile seizures are not epilepsy; instead, fever and illness prophylaxis are taught to parents for management.
A child with a first unprovoked seizure may not be treated immediately with medication. The risk of a second seizure is about 33%. The risks of taking antiepileptic medications must be weighed with the child’s history, neurologic examination findings, seizure type, and EEG findings. The drug of choice is also based upon these findings.
The mechanisms of action of antiepileptic drugs are complex and not completely understood. The possible mechanisms of action include altering intrinsic membrane properties and the synaptic function. These actions reduce neuronal firing, facilitate the increase of inhibitory and the decrease of excitatory neurotransmitters, or reduce the firing of the thalamic neurons. There are antiepileptic medications that are used for prophylaxis and rescue. If the child with epilepsy is seizure free for 1 to 2 years and is without reason to have further seizures, the child may be weaned from the antiepileptic medication(s). The following prophylactic antiepileptic medications are classified according to the seizure type and the known therapeutic drug levels.
Focal Seizures
| Carbamazepine | 4–12 mg/L |
| Lamotrigine | 4–20 mg/L |
| Levetiracetam | 5–40 mg/L |
| Oxcarbazepine | 12–30 mg/L |
| Pregabalin | Not established |
| Topiramate | 2–25 mcg/ml |
| Valproate, valproic acid | 50–125 mg/L |
| Zonisamide | 10–40 mcg/ml |
Generalized Seizures
| Lamotrigine | 4–20 mg/L |
| Levetiracetam | 5–40 mg/L |
| Topiramate | 2–25 mcg/ml |
| Valproate, valproic acid | 50–125 mg/L |
| Zonisamide | 10–40 mg/ml |
Broad-Spectrum (for More Than One Seizure Type)
| Lamotrigine | 4–20 mg/L |
| Levetiracetam | 5–40 mg/L |
| Topiramate | 2–25 mcg/ml |
| Valproate, valproic acid | 50–125 mg/L |
| Zonisamide | 10–40 mcg/ml |
Prophylactic medications not included on the list are felbamate, phenobarbital, phenytoin, primidone, and tiagabine. Phenobarbital has a clinically established safety profile, is used for neonatal seizures, and is an excellent rescue medication, but it tends to cause hyperactivity and cognitive effects in children over 1 year of age. Phenytoin is an excellent rescue medication especially when its prodrug form, fosphenytoin, is used; but phenytoin can cause undesirable side effects like coarsening and broadening of the facies, hirsutism, and cerebellar atrophy. Intravenous fluids must be chosen carefully with phenytoin but not fosphenytoin.
Felbamate is a powerful broad-spectrum medication. Initially it was approved by the FDA, and then it was restricted, since it caused serious adverse effects of aplastic anemia and hepatotoxicity in a number of patients. Felbamate can also cause side effects of insomnia and appetite depression. It must be used with caution, and families must be counseled about potential adverse effects.
Neither gabapentin nor tiagabine have demonstrated efficacy as monotherapeutic agents, but they can be used as adjunct medications for focal seizures. Methsuximide and ethosuximide are older antiepileptic medications that are no longer used. Ethosuximide has been used for absence epilepsy but does not treat the tonic-clonic seizures that occur in 50% of patients with absence epilepsy. Adrenocorticoptropin hormone (ACTH; Acthar Gel) is used on a limited basis as the treatment of choice for infantile spasms, a potentially devastating epilepsy syndrome. Pyridoxine-dependent epilepsy is rarely diagnosed, and the treatment of choice is pyridoxine daily for life. Seizures sometimes break through the week before the menstrual cycle, and acetazolamide may be used during that week to decrease breakthrough seizures.
Recent research has noted the potential for osteopenia and osteoporosis to occur in patients on long-term antiepileptic medications. The addition of vitamin D and calcium supplements has been suggested to prevent these complications.
Rescue medications for prolonged seizures or status epilepticus can be administered via intravenous, intranasal, and rectal routes. Medications administered via the intravenous routes are Depacon, diazepam, fosphenytoin, lorazepam, phenobarbital, and phenytoin. Diastat can be administered rectally. Midazolam is administered intranasally.
Adverse effects that may occur with antiepileptic drugs affect multiple systems. Central nervous system effects can include somnolence, confusion, gait problems, dizziness, and slurred speech. Gastrointestinal effects can include nausea and vomiting, changes in appetite, stomach pain, and hepatotoxicity. Adverse metabolic effects can include electrolyte changes such as sodium alterations, osteopenia, and osteoporosis. Adverse dermatologic effects can include skin rash, jaundice, and photosensitivity symptoms. Genitourinary adverse effects can consist of kidney stones and urinary output changes. Hematologic effects that have been observed are repeated infections, anemias, and bruising.
Ketogenic Diet
It has been noted as far back as Biblical times that starvation stopped seizures. The ketogenic diet is a high-fat, low-carbohydrate and low-protein diet that is calorie restricted for the brain to use ketones instead of glucose as an energy source. The exact mechanism of action is not known, but ketosis appears to produce an anticonvulsant effect in the brain. The diet requires strict adherence and can also be given in liquid form via gastrostomy tube for those patients without oral intake abilities. The diet is not especially palatable; it may be easier for children to ingest who have cognitive and mobility limitations. The ketogenic diet is attractive to parents, because if seizure control is improved with the diet, then antiepileptic medications can be weaned away over time. The ketogenic diet is not difficult to learn but requires commitment from the family, the school, and the community.
Adherence to the ketogenic diet necessitates a team approach. A dietitian trained in how to calculate, teach, and manage the ketogenic diet is essential. Team members must include nurses and physicians who are aware of how to manage the ketogenic diet and antiepileptic treatments. It may be started in the hospital or at home.
Possible adverse effects of the ketogenic diet include elevated cholesterol and triglycerides, lethargy, hypoglycemia, acidosis, nausea, vomiting, and constipation. Other adverse effects can include abdominal pain, dehydration, anorexia, electrolyte disturbances (e.g., hypocalcemia, hypomagnesemia, acidosis), platelet disturbances (aggregation disorders), and vitamin deficiencies.
Supplements are given to prevent vitamin and mineral (electrolyte) deficiencies. Supplements can include sugar-free vitamins with mineral, calcium, magnesium, potassium, salt, selenium, carnitine, and so forth.
It is important to know that children may feel hungry on this diet. If this occurs, the calories and make-up of the diet should be reviewed and compared with the child’s seizure status and height and weight. All involved in the child’s care must be aware the ketogenic diet is being used.
The child cannot receive anything with glucose in it, including toothpaste. All foods must be reviewed with the dietitian since even “sugar-free” foods can have hidden carbohydrates that can affect the ketogenic diet. Medications are monitored for carbohydrate amount and calculated into the diet. When sugar-free medications are available, they are used.
Documentation of the child’s current seizure treatment plan, including information about the ketogenic diet, should accompany the child if the child is transported to the emergency room or admitted to the hospital for an emergent condition, procedure, or prolonged seizure. In emergencies, the treatment of the patient overrides the ketogenic diet treatment. The diet can be restarted after the child’s condition is stabilized. The medical team should remain alert for breakthrough seizures or status epilepticus in the event the diet is changed.
Family home care involves monitoring of the ketogenic diet with daily urine ketone checks. The family also monitors the child’s growth in weight and height, since the rate of growth is slower than normal.
Laboratory monitoring is done periodically, in the fasting state. It typically includes complete blood cell count, and a comprehensive metabolic panel to include magnesium, lipid panel, and antiepileptic drug trough levels. A new laboratory value used in the ketogenic diet is the beta-hydroxybutyrate level, revealing serum ketosis. This laboratory evaluation is used to monitor the ketogenic diet and supplements.
Vagus Nerve Stimulation (VNS)
Since FDA approval in 1996, the VNS has been used as an adjunct treatment for intractable partial epilepsy. The VNS consists of a generator implanted subcutaneously in the left chest with an attached lead that is tunneled to the left vagus nerve. The left vagus nerve is used since it has more to do with innervation of the brain, whereas the right vagus nerve has more to do with the heart and intestines. The generator is programmed to deliver electrical stimulation to the lead, and impulses of predetermined duration are sent to widespread areas of the brain for a certain amount of time, such as 30 seconds of stimulation every 5 minutes. The mechanism of action is not understood, but there is metabolic activation of brain structures such as the thalamus, the brainstem, and limbic areas. There are also changes in neurotransmitter levels in the brain and the locus coeruleus, such as norepinephrine.
The degree of seizure reduction for the VNS is comparable to antiepileptic drugs. For those whose seizure control improves, AEDs may be decreased. A follow-up surgery to replace the battery or generator is needed every 8 to 10 years. Side effects that can occur during stimulation include hoarse voice, coughing, and minor throat discomfort. There are no cognitive side effects. There are no adherence issues, since the generator is programmed at the clinic office visit. There is a magnet that has a twofold purpose. It may be used during a seizure as a rescue method to stop or shorten the seizure, or to decrease postictal symptoms. The magnet is placed over the generator (it can be done over clothes) for a slow count of 3.
The generator then sets off an extra stimulation that is typically set higher and longer than the programmed stimulation to try to stop the seizure. Patients and families are taught to use the magnet as seizure rescue every 60 to 90 seconds for at least five attempts before going on to the next step in their seizure rescue treatment plan. The magnet can also be taped over the generator or placed in a shirt pocket over the generator to stop stimulation so a person’s voice is not affected by the VNS stimulation. This may be helpful to those who want to sing or give a professional presentation without a noticeable effect on their voice. The magnet must be in place for at least 5 minutes to stop the cycle. When the magnet is removed, the VNS cycle will restart about 5 minutes later. The VNS stimulation builds up over time, so there is no risk in stopping stimulation for short periods.
Patients with a VNS cannot have an MRI of the body, owing to potential tissue damage from overheating and vagus nerve damage. A MRI of the brain with a head coil is possible if the VNS generator turned off before the procedure. The VNS is then turned back on after the brain MRI is completed. Other x-ray studies and CT scans can be done without a problem.
Epilepsy Surgery
Epilepsy surgery can be palliative or curative. A corpus callosotomy is done for children with intractable atonic seizures that cause daily multiple falls and potential injuries. A corpus callosotomy stops the atonic seizures, but the epilepsy is not cured; the seizure discharge is no longer generalized but merely confined to one hemisphere. Following the resection of the corpus callosum, the seizures are expressed differently. Typically a two-thirds resection of the corpus callosum to decrease seizure potential may result in adverse side effects such as personality changes and difficulty remembering how to do things like eating. A child must remain on antiepileptic medications after a corpus callosotomy.
A focal cortical resection or functional hemispherectomy can potentially end seizure activity. These types of epilepsy surgeries require an extensive evaluation to ensure that the patient will not lose eloquent brain function. The evaluation requires a multidisciplinary team including an epileptologist, neurosurgeon, epilepsy nurse specialist, psychologist, psychiatrist, social worker, physical therapist, occupational therapist, speech therapist, and neuroradiologist.
A hemispherectomy is performed for certain epilepsy disorders such as Sturge-Weber syndrome, hemimegalencephaly, and Rasmussen’s encephalitis. The patient and the family must be made aware that following a hemispherectomy, there may be a hemiparesis that may or may not improve. Typically a patient with one of those disorders has a preexisting hemiparesis. The hemispherectomy carries a risk of hemorrhage, so the procedure tends to be done as a functional hemispherectomy, meaning the brain structures are disconnected but left in place to avoid potential hemorrhage.
A focal cortical resection is done in the area of the brain where the onset of seizure occurs. A temporal lobectomy has an 80% to 90% cure rate, and extratemporal resections result in a 40% to 70% cure rate. If a person is seizure free for 1 to 2 years after a focal cortical resection or hemispherectomy, antiepileptic medication may be eventually discontinued.
NURSING ASSESSMENT
1. See the Neurologic Assessment section in Appendix A.
2. Refer to Box 69-1 for specific types of seizure disorders.
NURSING DIAGNOSES
NURSING INTERVENTIONS
Seizures
2. Maintain detailed observation and recording of seizure (ictal) activity to assist in diagnosis or assessment of medication response.
3. Provide for sleep or rest after seizure. Reassure patient as consciousness returns.
4. Monitor child’s reaction to medication, VNS, ketogenic diet, and/or epilepsy surgery therapies.
5. Monitor drug levels and other laboratory evaluations as needed.
Status Epilepticus
1. Stabilize patent airway; suction as needed.
2. Provide supplemental 100% oxygen by face mask.
3. Monitor pulse oximetry and vital signs.
4. Place on electrocardiogram (ECG) monitoring.
5. Establish intravenous (IV) access for antiepileptic drug levels, other laboratory tests, and/or administration of rescue medication such as lorazepam, diazepam, fosphenytoin, phenytoin, or phenobarbital. Be prepared for further airway management if needed secondary to drug effects and prolonged seizure activity (more common if more than one medication is used or if multiple doses are given).
6. Know the facility’s treatment protocol to promote best practice and outcome.
Comorbidities of Epilepsy
1. Assess for comorbidities of epilepsy, including depression, anxiety, behavioral issues, ADD/ADHD, learning disorders, language disorders, fine and gross motor disorders, headaches and migraines, and social challenges.
2. If a comorbidity exists, consider further evaluation appropriate to the concern, such as health care provider evaluation, neuropsychologic assessment, psychiatric or psychologic assessment, speech and language evaluation, physical therapy evaluation, and/or occupational evaluation.
Discharge Planning and Home Care
1. Provide information about seizures, antiepileptic medications, and any other seizure therapies including VNS, ketogenic diet, and/or epilepsy surgery. Address any knowledge deficits family may have.
2. Stress importance of taking medication regularly and complying with scheduled follow-up appointments to monitor seizure disorder and growth and development, and to evaluate for any subtle side effects of medications or other therapies.
3. List what steps family should take to manage seizures as they occur and when to seek emergency medical care. Encourage family to practice seizure drills so each person knows what to do and expect when a seizure occurs.
4. Provide anticipatory guidance regarding safety.
5. Assist parent or caregiver in understanding process by which healthy self-concept is developed in presence of chronic condition. Reinforce need for consistent parenting and discipline.
6. Refer to Epilepsy Foundation of America for further information and support (www.efa.org).
7. Review potential issues that might arise for patient and family during adjustment to diagnosis, and need for support and intervention if adjustment problems occur. Educate family about the issue of stigma in epilepsy. Refer child and family for counseling as needed.
CLIENT OUTCOMES
1. Child will have safety interventions in place to prevent injury from seizure activity.
2. Seizure activity will be prevented or controlled with antiepileptic medications and/or other seizure therapies like VNS, ketogenic diet, and/or epilepsy surgery.
3. Child will have positive self-esteem and self-image that will enhance wellness secondary to education received regarding epilepsy disorder.
4. Child will obtain optimal development and independence secondary to seizure assessment and treatment.
5. The family of a child with epilepsy will obtain optimal development and quality of life secondary to epilepsy education and support resources given.
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